1. Field of the Invention
The present invention relates to entrapping immobilization pellets for purifying breeding water, a process and an apparatus for purifying breeding water, and an aquarium set. More particularly, the present invention relates to entrapping immobilization pellets for purifying breeding water which remove ammonium nitrogen contained in breeding water to breed aquatic animals by decomposition of microorganisms and improve the beauty; a process and an apparatus for purifying breeding water; and an aquarium set.
2. Description of the Related Art
Conventionally, attachment-type purification materials in which nitrifying bacteria (ammonium oxidizing bacteria or nitrite oxidizing bacteria) are naturally attached to filters, sponges, porous ceramics, or the like have been used as materials for removing ammonium nitrogen or nitrite nitrogen contained in aquarium to breed aquatic animals. Such attachment-type purification materials are formed by placing filters, sponges, porous ceramics, or the like in aquarium or in external apparatuses in which breeding water is circulated and bringing them into contact with breeding water.
An attachment-type purification material generally does not have purification performance to remove ammonium nitrogen, nitrite nitrogen, or the like contained in breeding water until nitrifying bacteria are sufficiently attached onto the material. Therefore, the problem is that the ammonium nitrogen concentration in breeding water is increased until nitrifying bacteria are sufficiently attached onto the material.
Specifically, it usually takes about two to four weeks to make nitrifying bacteria attached to the material so that the material can treat ammonium nitrogen. Even if the material can treat ammonium nitrogen, the material can oxidize ammonium nitrogen only to nitrite at the initial stage, and nitrite nitrogen more toxic than ammonium nitrogen is easily accumulated in breeding water. It takes about further two to four weeks to make nitrite oxidizing bacteria attached to the material and thus oxidize nitrite nitrogen to nitrate nitrogen having relatively small toxicity. That is, water quality is not favorable for aquatic animals for two weeks to two months after placing the material in an aquarium.
For example, Japanese Patent Application Laid-Open No. 2005-117925 proposes, as measures against this problem, a filter for purifying an aquarium for fish and aquatic animals obtained by immersing carbonized cotton in a purification tank where nitrifying bacteria are grown, so that the nitrifying bacteria are naturally attached to and immobilized in the carbonized cotton, and converting the carbonized cotton into a sheet. This patent specification describes that a filter to which nitrifying bacteria are previously attached is placed in an aquarium and thus can immediately exhibit purification performance.
However, it takes about one week to two months to attach bacteria to the filter for purifying an aquarium as in Japanese Patent Application Laid-Open No. 2005-117925 and it is necessary to store the filter as immersed in an ammonium liquid. Further, pores of the filter are easily clogged as the filter is continuously used, and thus it is necessary to clean and exchange the filter periodically. Nitrifying bacteria attached to the filter are also removed together, and it takes a long time to attach nitrifying bacteria again. Therefore, the problem is that the filter cannot be immediately put in an aquarium and used when necessary.
Further, a filter to which bacteria are attached is generally unnoticeably placed in an ornamental aquarium on purpose, since the filter causes deterioration in the beauty.
The present invention has been achieved in view of such circumstances. An object of the present invention is to provide entrapping immobilization pellets which can exhibit purification performance immediately after being placed in an aquarium and furthermore can provide a color, luster, and the like for the main body or periphery of the aquarium to improve the beauty of the whole aquarium environment; a process and an apparatus for purifying breeding water; and an aquarium set.